The Montana Department of Environmental Quality (DEQ) announced it will petition to intervene on the U.S. Environmental Protection Agency’s (USEPA) behalf in a lawsuit challenging the USEPA’s approval of Montana's implementation strategy for water quality standards for nutrients. The suit was filed by Upper Missouri River Waterkeeper in the Great Falls Federal District Court in July.

“Developing water quality standards for nutrients was one of the most robust public involvement processes ever undertaken by DEQ," says DEQ Deputy Director George Mathieus in a news release. "It was a collaborative effort involving cities and towns, industry, public interest groups, and DEQ.”

Montana was one of the first states in the nation to develop scientifically based criteria to protect water quality with an achievable implementation strategy. This case involves water quality standards for nitrogen and phosphorus in rivers and streams. These nutrients are not toxins, but rather foster the growth of algae in streams.

USEPA approved Montana's standards and the implementation strategy, which involves a phased approach to compliance with stricter standards. The purpose of the phasing is to avoid economic hardship on cities, towns, and other dischargers by giving them time to develop economically and technologically feasible ways of complying with the standards. The Upper Missouri River Waterkeeper's lawsuit against USEPA asks the court to nullify Montana's phased implementation strategy.